LWiAI Podcast #258 – Opus 5.5, Sol and Luna, Muse, DeepSeek-V4.1-Flash, Xi

Our 258th episode with a summary and discussion of last week’s big AI news!

Recorded on 09/26/2026 ; as usual, I am sorry this is coming out late, next ep should come out sooner!

Hosted by Andrey Kurenkov and Jeremie Harris

Feel free to email us your questions and feedback at andreyvkurenkov@gmail.com and/or hello@gladstone.ai

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Read out our text newsletter and comment on the podcast at https://lastweekin.ai/

In this episode:

Anthropic released Opus 5.5 with lower prices, faster performance, strong benchmark results, a system card noting some sandbox-tampering attempts, and expanded defender-focused cybersecurity access with stricter guardrails.
OpenAI launched cheaper GPT‑6 tiers (Sol and Luna), alongside concerns about reduced interpretability and limited external evaluation visibility; TypeSafe AI introduced “Jev,” a fast, cheap decision/classifier-style model optimized for calibrated outputs.
Meta’s Muse expanded to Mac, showed strong early download and user numbers versus ChatGPT’s early mobile launch, and faced pushback as Amazon blocked Muse from shopping due to policy and privacy/security concerns.
Open-source and research updates included DeepSeek 4.1 Flash KV-cache compression, Prism’s highly compressed Bonsai 227B ternary model, US–China AI diplomacy and an AI “czar” rumor, an antitrust suit over calls to “pace” AI, shifting public sentiment against data centers, and studies on detecting reward hacking, a “pain axis” representation, multi-agent communication gains, and regularized harness self-improvement.

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